Protection Against Foot And Mouth Disease Virus In Guinea Pigs Via Oral A Dm Inistration Of Recom Binant Lactobacillus Plantarum Expressing VP1

Mucosal vaccination is an effective strategy for generating antigen-specific immune responses against mucosal infections of foot and mouth disease virus(FMDV). In this study, two recombinant L. plantarum strains—NC8 and WCFS1—were constructed to express a synthetic VP1 gene of FMDV A virus. We sought to evaluate the immunological and clinical impact of the plasmids encoding FMDV- VP1 capsid protein using L. plantarum as mucosal adjuvant via oral vaccination in a guinea pig model.The expressions of VP1 in NC8 and WCFS1 w ere detected by SDS-PAGE and western blotting. Immunoreactive bands were detected in the cell fractions of NC8 containing recombinant plasmids and WCFS1 containing recombinant plasmids.The mucosal immunity of guinea pigs was studied by measuring the anti-FMDV- VP1 Ig A response in serum. Anti-FMDV- VP1 Ig A, Ig M and Ig G reached high levels in experim ental groups, NC8-p SIP411-VP1 and WCFS1-p SIP411-VP1, and no significant anti-FMDV- VP1 antibodies were observed in the control groups. These results indicated that orally administered NC8-p SIP411-VP1 and WCFS1-p SIP411-VP1 were able to elic it both FMDV-specific systemic and mucosal antibody responses. Moreover, the mucosal immune responses occurred earlier than systemic responses but also declined more rapidly. To investigate cellular immune responses after oral immunization with Lactobacillus strains incorporating the recombinant plasmid, the CD4+ T cells and CD8+ cells in both NC8-p SIP411-VP1 and WCFS1-p SIP411-VP1 groups rose to a higher level than the control groups. Both two groups produced significantly high levels of T cell proliferation when stimulated by activated FMDV as a specific antigen, while no obvious proliferation occurred in the control groups. These results indicated that these Lactobacillus strains expressing VP1 protein could induce antigen-specific T cell responses. Antibody responses of guinea pigs orally immunized with NC8-p SIP411-VP1 or WCFS1-p SIP411-VP1 exhibited higher FMDV-neutralizing activity than the control groups’ responses, as shown by cytopathic effect(CPE) inhibition, indicating that NC8-p SIP411-VP1 and WCFS1-p SIP411-VP1 could induce neutralizing antibodies to FMDV. The guinea pigs were challenged with 100 GPID50(50 % guinea pigs infectious dose) of homotypic virus on day 30 after the first immunization, and the protective effects of the oral vaccines were evaluated. NC8-p SIP411-VP1 and WCFS1-p SIP411-VP1 vaccination provided at least partial protection against FMDV.We concluded that the oral live carrier vaccine using L. plantarum was a promising strategy for the presentation of FMDV-VP1 antigen to provide an effective, inexpensive and stable alternative to current approaches of immunization for FMDV.